Cleaning the exaust port (echo)

What is involved in cleaning the exaust port on an echo engine? It says let a echo service center do it but I would like to learn my self. I pretty much had the entire thing apart today but I would like to know a little more. Also how often should this be done?

You have the exhaust muffler off yes if so,pull the rope till the piston blocks the port with a small screw driver or pick scrap the carbon being careful not to touch the piston walls,with air keep blowing and scraping i use pb blaster to help.